Erectile dysfunction is the most prevalent form of male sexual dysfunction and is particularly common in men with chronic diseases such as end stage renal disease. It was believed by medical and mental health professionals alike, that erectile dysfunction either had psychogenic or organic etiology. More recently, professionals realize that causality is not an either/or situation, but that both psychogenic and organic factors often interact and a diagnostic strategy must identify the relative influences of each. The purpose of this project is to develop a psychogenicity and organicity scale for erectile failure that reflect the interactive nature of both factors in determining erectile dysfunction; to see if inexpensive and non-invasive assessment procedures can reliably determine the degree and type of organicity; and to apply these procedures to men with end stage renal disease and pinpoint specific organic and psychogenic causes for their erectile dysfunction. In Studies 1 and 2, organicity and psychogenicity scales will be developed. A 5-component medical evaluation and a psychological battery will be administered to men at high risk for organicity, at low risk for organicity, and to a group of normal controls. Discriminant function analyses will be performed on these data to determine an organicity and psychogenicity scale. In Study 3, an examination of more convenient, and cost-effective procedures will be undertaken to see if any can replace the more complex procedures used to develop the scales. A new sexual functioning questionnaire, and a chronic illness questionnaire will be evaluated as possible predictors of organicity and psychogenicity scores. In Study 4, a cross-validation of the work in Studies 1 through 3 will be undertaken, as will an attempt to generalize the value of these scales to a population of men who do not fit into the two extreme groups used in Study 1 and 2. In the fifth study, men with end stage renal disease (ESRD) and erectile dysfunction, will be assessed with the cost effective assessment battery. Those with a high organicity score will be further evaluated using the full organic assessment battery to assess the particular reasons for their organic disability. An organicity/psychogenicity pattern will be established for each individual and a treatment program suggested by the individual needs of the patient. Additionally, this study will help generate information about the specific etiology of erectile failure in ESRD patients.